AON Center - Fog

Chicago 1986, AON Center seen from John Hancock Center, built 1970-1973, 83 floors, 346 m - scanned slide, Minolta X700

Architect: Edward Durell Stone

The original marble cladding (here on this image) bowed under the temperature swings experienced in the Chicago climate. The cladding was 32mm thick Itallian Carrera Marble (similar to what Michaelangelo used), but 20 years after original construction it had severly deteriorated. The marble was replaced with 51mm thick Mt. Airy Granite at a cost of $80M between 1990 and 1992 (43000 individual 1.27m x 1.14m panels). The original construction cost in 1973 was a mere $120M.